Ring about the first floral piece (5)
I believe the answer is:
petal
'floral piece' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'ring about the first' is the wordplay.
'ring' becomes 'peal' (pealing is a kind of ringing).
'about' means one lot of letters goes inside another.
'first' says to take the initial letters.
The first letter of 'the' is 't'.
'peal' placed around 't' is 'PETAL'.
Can you help me to learn more?
(Other definitions for petal that I've seen before include "Colourful flower part" , "Small seal set in a ring" , "Floral segment" , "Part of a plant's perianth that is usually brightly coloured" , "Part of flag" .)